In-pile tritium release behavior and the post-irradiation experiments of Li4SiO4 fabricated by melting process

Zhao Linjie,Yang Mao,Xiao Chengjian,Gong Yu,Ran Guangming,Chen Xiaojun,Li Jiamao,Yue Lei,Chen Chao,Hou Jingwei,Wang Heyi,Long Xinggui,Peng Shuming 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

Understanding the tritium release and retention behavior of candidate tritium breeder materials is crucial for breeder blanket design. Recently, a melt spraying process was developed to prepare Li4SiO4 pebbles, which were subsequently subjected to the in-pile tritium production and extraction platform in China Mianyang Research Reactor (CMRR) to investigate their in-situ tritium release behavior and irradiation performance. The results demonstrate that HT is the main tritium release form, and adding hydrogen to the purge gas reduces tritium retention while increasing the HT percent in the purge gas. Post-irradiation experiments reveal that the irradiated pebbles darken in color and their grains swell, but the mechanical properties remain largely unchanged. It is concluded that the tritium residence time of Li4SiO4 made by melt spraying method at 467 ◦C is approximately 23.34 h. High-density Li4SiO4 pebbles exhibit tritium release at relatively low temperatures (<600 ◦C) that is mainly controlled by bulk diffusion. The diffusion coefficient at 525 ◦C and 550 ◦C is 1.19 × 10 11 cm2/s and 5.34 × 10 11 cm2/s, respectively, with corresponding tritium residence times of 21.3 hours and 4.7 hours.

NEDD8-activating enzyme inhibitor, MLN4924 (Pevonedistat) induces NOXA-dependent apoptosis through up-regulation of ATF-4

Liu, Xiaojun,Jiang, Yanan,Wu, Jianfu,Zhang, Wenjuan,Liang, Yupei,Jia, Lijun,Yu, Jinha,Jeong, L.S.,Li, Lihui Elsevier 2017 Biochemical and biophysical research communication Vol. No.

<P><B>Abstract</B></P> <P>It has been reported that MLN4924 can inhibit cell growth and metastasis in various kinds of cancer. We have reported that MLN4924 is able to inhibit angiogenesis through the induction of cell apoptosis both in vitro and in vivo models. Moreover, Neddylation inhibition using MLN4924 triggered the accumulation of pro-apoptotic protein NOXA in Human umbilical vein endothelial cells (HUVECs). However, the mechanism of MLN4924-induced NOXA up-regulation has not been addressed in HUVECs yet. In this study, we investigated how MLN4924 induced NOXA expression and cellular apoptosis in HUVECs treated with MLN4924 at indicated concentrations. MLN4924-induced apoptosis was evaluated by Annexin V-FITC/PI analysis and expression of genes associated with apoptosis was assessed by Quantitative RT-PCR and western blotting. As a result, MLN4924 triggered NOXA-dependent apoptosis in a dose-dependent manner in HUVECs. Mechanistically, inactivation of Neddylation pathway caused up-regulation of activating transcription factor 4 (ATF-4), a substrate of Cullin-Ring E3 ubiquitin ligases (CRL). NOXA was subsequently transactivated by ATF-4 and further induced apoptosis. More importantly, knockdown of ATF-4 by siRNA significantly decreased NOXA expression and apoptotic induction in HUVECs. In summary, our study reveals a new mechanism underlying MLN4924-induced NOXA accumulation in HUVECs, which may help extend further study of MLN4924 for angiogenesis inhibition treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> MLN4924 triggered NOXA-dependent apoptosis in a dose-dependent manner in HUVECs. </LI> <LI> Inactivation of neddylation caused up-regulation of ATF4, a substrate of CRL. </LI> <LI> NOXA was transactivated by ATF4 and further induced apoptosis. </LI> <LI> Knockdown of ATF-4 significantly decreased NOXA expression and apoptotic induction. </LI> <LI> We revealed a new mechanism underlying MLN4924-induced NOXA accumulation in HUVECs. </LI> </UL> </P>

Calculation of cavitation evolution and associated turbulent kinetic energy transport around a NACA66 hydrofoil

Xiaojun Li,Bowen Li,Benxu Yu,Yun Ren,Bo Chen 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

The physical mechanism of flow unsteadiness is one of the key problems in cavitating flow. Significant efforts have been exerted to explain the cavitation-vortex interaction mechanism. As well, the process of kinetic energy transport during the evolution of unsteady cavitating flow must be elucidated. In this work, 2D calculations of cavitating flow around a NACA66 hydrofoil were performed based on the open source software OpenFOAM. The modified shear stress transport k-ω turbulence model, which considers curvature and turbulent eddy viscosity corrections, was employed to close the governing equations. The Schnerr-Sauer cavitation model was adopted to capture the cavitation phase change process. Numerical results showed reasonable consistency with the results of the experiments conducted by Leroux et al. (2004). The results showed that cavitation promotes turbulence intensity and flow unsteadiness around the hydrofoil. During the attached sheet cavity growth stage, high-value regions of turbulent kinetic energy are located substantially at the interface of the cavity, particularly at the rear portion of the cavity region. During the cloud cavity shed-off stage, the cavity begins to break off and the maximum value of turbulent kinetic energy is observed inside the shed cavity. Finally, the influence of cavitation on the turbulence intensity is illustrated using the turbulent kinetic energy transport equation, which shows that the pressure diffusion and turbulent transport terms dominate as cavitation occurs. In addition, cavitation promotes turbulence production and increases dissipation with fluid viscosity and flow unsteadiness. The viscous transport term only acts in the cavitation shedding stage under large-scale vortex shedding. Overall, these findings are of considerable interest in engineering applications.

Theoretical Study on the Mechanism of the Addition Reaction between Cyclopropenylidene and Formaldehyde

Xiaojun Tan,Zhen Li,Qiao Sun,Ping Li,Weihua Wang 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.6

The reaction mechanism between cyclopropenylidene and formaldehyde has been systematically investigated employing the MP2/6-311+G* level of theory to better understand the cyclopropenylidene reactivity with carbonyl compound. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are further corrected by the CCSD(T)/6-311+G* single-point calculations. It was found that one important reaction intermediate (INTa) has been located firstly via a transition state (TSa). After that, the common intermediate (INTb) for the two pathways (1) and (2) has been formed via TSb. At last, two different products possessing three- and four-membered ring characters have been obtained through two possible reaction pathways. In the reaction pathway (1), a three-membered ring alkyne compound has been obtained. As for the reaction pathway (2), it is the formation of the four-membered ring conjugated diene compound. The energy barrier of the ratedetermining step of pathway (1) is lower than that of the pathway (2), and the ultima product of pathway (2) is more stable than that of the pathway (1).

Effect of the blade loading distribution on hydrodynamic performance of a centrifugal pump with cylindrical blades

Xiaojun Li,Panlong Gao,ZuChao Zhu,Yi Li 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3

The effect of the blade loading distribution on head, radial force and pressure pulsation of a low specific-speed centrifugal pump with cylindrical impeller blades were investigated in the present study. Blade shapes were obtained by adopting the 1D inverse design method, impellers with different blade loading curves were obtained while the distribution of the blade loading was carefully tailored. Threedimensional URANS simulation method based on the Shear stress transport (SST) k-ω turbulence model was employed for the analyzation of flow patterns. Numerical results including the pressure distribution and velocity profile were validated by comparing with the available experimental data, and an acceptable agreement was obtained. Three typical parameters of the blade loading curve, including the location of the fore-loading point (m pre ), location of the aft-loading point (m post ) and slope of the rectilinear segment (K), were analyzed. Results showed that the well-designed blade loading curve, such as the fore-loading impeller, can effectively reduce the pressure pulsation amplitude and the radial force. The significant effect of the variation of the aft-loading point on pump hydrodynamic performance was also investigated. Meanwhile, pressure and velocity distributions at different slopes of the blade loading curves show that the fore-loading impeller produces more uniform flow issuing from the impeller than that of the pump with aft-loading impeller, thus reduces the radial force and pressure pulsation of the pump.

Theoretical Studies on the Alkylidene Silylenoid H2C = SiLiF and Its Insertion Reaction with R-H (R = F, OH, NH2)

Xiaojun Tan,Weihua Wang,Ping Li,Qingyan Li,Lei Cheng,Shufen Wang,Weiwang Cai,Jinping Xing 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.5

The geometries and isomerization of the alkylidene silylenoid H2C = SiLiF as well as its insertion reactions with R-H (R = F, OH, NH2) have been systematically investigated at the B3LYP/6-311+G* level of theory. The potential barriers of the three insertion reactions are 97.5, 103.3, and 126.1 kJ/mol, respectively. Here, all the mechanisms of the three reactions are identical to each other, i.e., an intermediate has been formed first during the insertion reaction. Then, the intermediate could dissociate into the substituted silylene (H2C = SiHR) and LiF with a barrier corresponding to their respective dissociation energies. Correspondingly, the reaction energies for the three reactions are ‒36.4, ‒24.3, and 3.7kJ/mol, respectively. Compared with the insertion reaction of H2C = Si: and R-H (R = F, OH and NH2), the introduction of LiF makes the insertion reaction occur more easily. Furthermore, the effects of halogen (F, Cl, Br) substitution and inorganic salts employed on the reaction activity have also been discussed. As a result, the relative reactivity among the three insertion reactions should be as follows: H-F > H-OH > H-NH2.

Differential Expression of miR-34c and Its Predicted Target Genes in Testicular Tissue at Different Development Stages of Swine

Xiaojun Zhang,Wei Zhao,Chuanmin Li,Haibin Yu,YanYan Qiao,Aonan Li,Chunyan Lu,Zhihui Zhao,Boxing Sun 아세아·태평양축산학회 2015 Animal Bioscience Vol.28 No.11

To verified the target genes of miR-34c, bioinformatics software was used to predict the targets of miR-34c. Three possible target genes of miR-34c related to spermatogenesis and male reproductive development: zinc finger protein 148 (ZNF148), kruppel-like factor 4 (KLF4), and platelet-derived growth factor receptor alpha (PDGFRA) were predicted. Then, the expression of miR-34c and its target genes were detected in swine testicular tissue at different developmental stages by quantitative polymerase chain reaction. The results suggested that the expression of PDGFRA has the highest negative correlation with miR-34c. Then immunohistochemical staining was done to observe the morphology of swine testicular tissue at 2-days and 3, 4, 5-months of age, which indicated that PDGFRA was mainly expressed in the support cells near the basement membrane during the early development stages of testicular tissue, but that the expression of PDGFRA was gradually reduced in later stages. Therefore, western blot analyzed that the highest expression of PDGFRA was generated in 2-days old testicular tissues and the expression levels reduced at 3 and 4-months old, which correlated with the results of immunohistochemical staining. In conclusion, PDGFRA is a target gene of miR-34c.

Genome-wide identification and evolutionary analysis of WOX gene family in cucurbit crops

Li Chun,He Zhen,Liang Genyun,Yang Nan,Cai Peng,Liang Ying,Li Yuejian,Fang Chao,Liu Duchen,Xia Feng,Liu Xiaojun 한국원예학회 2024 Horticulture, Environment, and Biotechnology Vol.65 No.1

The WUSCHEL-related homeobox (WOX) gene family is essential for plant growth and development. However, the identifi cation and evolutionary analysis of WOX genes in the Cucurbitaceae have not been well investigated. In the present work, we performed a genome-wide analysis to identify WOX genes in eleven cucurbit crops. In total, 127 WOX genes were identifi ed in eleven cucurbit crops, and classifi ed into three diff erent clades: the ancient clade, the intermediate clade and the WUS clade. The same clade has comparable gene organization and conserved motif patterns. The cis -acting ele ment analysis revealed that WOX genes were involved in light, hormone and stress in cucurbit crops. Gene duplication analysis indicated that dispersed duplication and whole genome duplication were the two primary causes of WOX genes expansion. There were 24 and 129 gene pairs found within cucurbit crops, and between Cucumis sativus and other cucur bit crops, respectively. After gene duplication, all WOX genes were subjected to substantial purifying selection pressure according to the selective pressure analysis. Functional divergence analysis revealed that ancient and intermediate clades may have descended from some essential amino acid sites rather than diff erent evolution rate. Our research provides a comprehensive analysis of WOX genes which will be helpful for further research into their function study in Cucurbita ceae plants.

Theoretical Study on the Mechanism of the Addition Reaction between Cyclopropenylidene and Formaldehyde

Tan, Xiaojun,Li, Zhen,Sun, Qiao,Li, Ping,Wang, Weihua Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.6

The reaction mechanism between cyclopropenylidene and formaldehyde has been systematically investigated employing the MP2/6-311+$G^*$ level of theory to better understand the cyclopropenylidene reactivity with carbonyl compound. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are further corrected by the CCSD(T)/6-311+$G^*$ single-point calculations. It was found that one important reaction intermediate (INTa) has been located firstly $via$ a transition state (TSa). After that, the common intermediate (INTb) for the two pathways (1) and (2) has been formed $via$ TSb. At last, two different products possessing three- and four-membered ring characters have been obtained through two possible reaction pathways. In the reaction pathway (1), a three-membered ring alkyne compound has been obtained. As for the reaction pathway (2), it is the formation of the four-membered ring conjugated diene compound. The energy barrier of the ratedetermining step of pathway (1) is lower than that of the pathway (2), and the ultima product of pathway (2) is more stable than that of the pathway (1).

Theoretical Studies on the Alkylidene Silylenoid H₂C = SiLiF and Its Insertion Reaction with R-H (R = F, OH, NH₂)

Tan, Xiaojun,Wang, Weihua,Li, Ping,Li, Qingyan,Cheng, Lei,Wang, Shufen,Cai, Weiwang,Xing, Jinping Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.5

The geometries and isomerization of the alkylidene silylenoid $H_2C$ = SiLiF as well as its insertion reactions with R-H (R = F, OH, $NH_2$) have been systematically investigated at the B3LYP/6-311+$G^*$ level of theory. The potential barriers of the three insertion reactions are 97.5, 103.3, and 126.1 kJ/mol, respectively. Here, all the mechanisms of the three reactions are identical to each other, i.e., an intermediate has been formed first during the insertion reaction. Then, the intermediate could dissociate into the substituted silylene ($H_2C$ = SiHR) and LiF with a barrier corresponding to their respective dissociation energies. Correspondingly, the reaction energies for the three reactions are -36.4, -24.3, and 3.7 kJ/mol, respectively. Compared with the insertion reaction of $H_2C$ = Si: and R-H (R = F, OH and $NH_2$), the introduction of LiF makes the insertion reaction occur more easily. Furthermore, the effects of halogen (F, Cl, Br) substitution and inorganic salts employed on the reaction activity have also been discussed. As a result, the relative reactivity among the three insertion reactions should be as follows: H-F > H-OH > H-$NH_2$.